M.M. Mekonnen
The green, blue and grey
A.Y. Hoekstra
water footprint of farm
December 2010
animals and animal products
Volume 1: Main Report
Value of Water
Research Report Series No. 48
THE GREEN, BLUE AND GREY WATER FOOTPRINT
OF FARM ANIMALS AND ANIMAL PRODUCTS
VOLUME 1: MAIN REPORT
M.M. MEKONNEN1
A.Y. HOEKSTRA1,2
DECEMBER 2010
VALUE OF WATER RESEARCH REPORT SERIES NO. 48
1
Twente Water Centre, University of Twente, Enschede, The Netherlands
2
Contact author: Arjen Hoekstra, a.y.hoekstra@utwente.nl
© 2010 M.M. Mekonnen and A.Y. Hoekstra.
Published by:
UNESCO-IHE Institute for Water Education
P.O. Box 3015
2601 DA Delft
The Netherlands
The Value of Water Research Report Series is published by UNESCO-IHE Institute for Water Education, in
collaboration with University of Twente, Enschede, and Delft University of Technology, Delft.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in
any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior
permission of the authors. Printing the electronic version for personal use is allowed.
Please cite this publication as follows:
Mekonnen, M.M. and Hoekstra, A.Y. (2010) The green, blue and grey water footprint of farm animals and
animal products, Value of Water Research Report Series No. 48, UNESCO-IHE, Delft, the Netherlands.
Contents
Summary .................................................................................................................................................................. 5
1. Introduction ........................................................................................................................................................ 7
2. Method and data ................................................................................................................................................. 9
2.1 Method ....................................................................................................................................................... 9
2.2 Data .......................................................................................................................................................... 14
3. Results .............................................................................................................................................................. 19
3.1 Quantity and composition of animal feed ................................................................................................ 19
3.2 The water footprint of animal feed ........................................................................................................... 21
3.3 The water footprint of live animals at the end of their lifetime and animal products per ton .................. 21
3.4 Water footprint of animal versus crop products per unit of nutritional value .......................................... 28
3.5 The total water footprint of animal production ........................................................................................ 29
4. Discussion ........................................................................................................................................................ 35
5. Conclusion ........................................................................................................................................................ 39
References .............................................................................................................................................................. 41
Summary
The projected increase in the production and consumption of animal products is likely to put further pressure on
the globe’s freshwater resources. The size and characteristics of the water footprint vary across animal types and
production systems. The current study provides a comprehensive account of the global green, blue and grey
water footprints of different sorts of farm animals and animal products, distinguishing between different
production systems and considering the conditions in all countries of the world separately. The following animal
categories were considered: beef cattle, dairy cattle, pig, sheep, goat, broiler chicken, layer chicken and horses.
The study shows that the water footprint of meat from beef cattle (15400 m3/ton as a global average) is much
larger than the footprints of meat from sheep (10400 m3/ton), pig (6000 m3/ton), goat (5500 m3/ton) or chicken
(4300 m3/ton). The global average water footprint of chicken egg is 3300 m3/ton, while the water footprint of
cow milk amounts to 1000 m3/ton. Per ton of product, animal products generally have a larger water footprint
than crop products. The same is true when we look at the water footprint per calorie. The average water footprint
per calorie for beef is twenty times larger than for cereals and starchy roots. When we look at the water
requirements for protein, we find that the water footprint per gram of protein for milk, eggs and chicken meat is
about 1.5 times larger than for pulses. For beef, the water footprint per gram of protein is 6 times larger than for
pulses. In the case of fat, we find that butter has a relatively small water footprint per gram of fat, even lower
than for oil crops. All other animal products, however, have larger water footprints per gram of fat when
compared to oil crops. The study shows that from a freshwater resource perspective, it is more efficient to obtain
calories, protein and fat through crop products than animal products.
Global animal production requires about 2422 Gm3 of water per year (87.2% green, 6.2% blue, 6.6% grey
water). One third of this volume is for the beef cattle sector; another 19% for the dairy cattle sector. Most of the
total volume of water (98%) refers to the water footprint of the feed for the animals. Drinking water for the
animals, service water and feed mixing water account only for 1.1%, 0.8% and 0.03%, respectively.
The water footprints of animal products can be understood from three main factors: feed conversion efficiency of
the animal, feed composition, and origin of the feed. The type of production system (grazing, mixed, industrial)
is important because it influences all three factors. A first explanatory factor in the water footprints of animal
products is the feed conversion efficiency. The more feed is required per unit of animal product, the more water
is necessary (to produce the feed). The unfavourable feed conversion efficiency for beef cattle is largely
responsible for the relatively large water footprint of beef. Sheep and goats have an unfavourable feed
conversion efficiency as well, although better than cattle. A second factor is the feed composition, in particular
the ratio of concentrates versus roughages and the percentage of valuable crop components versus crop residues
in the concentrate. Chicken and pig have relatively large fractions of cereals and oil meal in their feed, which
results in relatively large water footprints of their feed and abolishes the effect of the favourable feed conversion
efficiencies. A third factor that influences the water footprint of an animal product is the origin of the feed. The
water footprint of a specific animal product varies across countries due to differences in climate and agricultural
practice in the regions from where the various feed components are obtained. Since sometimes a relatively large
6 / The water footprint of farm animals and animal products
fraction of the feed is imported while at other times feed is mostly obtained locally, not only the size but also the
spatial dimension of the water footprint depends on the sourcing of the feed.
It is relevant to consider from which type of production system an animal product is obtained: from a grazing,
mixed or industrial system. Animal products from industrial production systems generally have a smaller total
water footprint per unit of product than products from grazing systems, with an exception for dairy products
(where there is little difference). However, products from industrial systems always have a larger blue and grey
water footprint per ton of product when compared to grazing systems, this time with an exception for chicken
products. It is the lower green water footprint in industrial systems that explains the smaller total footprint. Given
the fact that freshwater problems generally relate to blue water scarcity and water pollution and to a lesser extent
to competition over green water, this means that grazing systems are preferable over industrial production
systems from a water resources point of view. In the case of cattle, pigs, sheep and goats, the total water
footprints per ton of product are larger for grazing systems because of the worse feed conversion efficiencies, but
the fact that these systems depend more strongly on roughages (which are less irrigated and less fertilised than
the feed crops contained in concentrate feed) makes that the blue and grey water footprints of products from
grazing systems are smaller. This compensation through the feed composition does not occur for the case of
chicken. The reason is that chicken strongly rely on concentrate feed in all production systems. Mixed production
systems generally take a position in between industrial and grazing systems. Not accounted for in this study is
that industrialized animal production often produces large amounts of animal waste that cannot be fully recycled
in the nearby land. Such large amounts of waste produced in a concentrated place are known to pollute
freshwater resources if not handled properly.
By focusing on freshwater appropriation, the study obviously excludes many other relevant issues in farm animal
production, such as micro- and macro-cost of production, livelihood of smallholder farmers, animal welfare,
public health and environmental issues other than freshwater.
1. Introduction
In the last few decades the world has seen a significant shift in food consumption patterns towards more animal
products such as meat, milk and egg, mainly due to growing economies and rising individual incomes. In
developing countries, in particular, consumption of meat, milk and dairy products has been growing the last few
decades at 5-6 percent and 3.4-3.8 percent annually respectively (Bruinsma, 2003). The shift in consumption
patterns coupled with high population growth and rapid urbanization in most developing countries is driving the
total demand for animal products upward.
The global meat production has nearly doubled between 1980 and 2004, with the largest share of growth in
developing countries (FAO, 2005). Related to the increased production there is a shift away from grazing
systems. Although the traditional pastoral system plays a role, most of the increase in meat and milk production
in the last three decades was achieved through production increase in the mixed and industrial production
systems (Bouwman et al., 2005). The shift to more intensive production systems influences the composition of
animal feed. Traditionally, animals have relied on locally available feed, such as grass, crop residues and wastes
from human food. The more intensive production systems depend on concentrate feeds that are traded locally
and internationally. In many countries, there is a tendency towards decreasing reliance on grazing and increasing
dependence on concentrate feeds. Intensive animal production systems, in which animals are raised in
confinement, currently account for 74 percent of the world’s total poultry production, 40 percent of pig meat and
more than two-thirds of egg production (Seré and Steinfeld, 1996). If this trend continues in the future, its
implication will be far-reaching for both land and water resources requirements.
Animal production requires large volumes of water for feed production, drinking water and servicing animals.
By far the largest water demand in animal production is the water needed to produce animal feed. Because of
the increasing demand for animal products and the growing sector of industrial farming, the demand for
feedstuffs grows as well, including cereals, starchy roots, fodder crops, oilseeds and oil meals. Such high
demand for feed in turn causes a rising demand for water. Besides, intensification of animal production systems
will lead to surface and ground water pollution, both from the use of fertilizers in feed crops production and
improper storage and application of manures.
The global meat trade is projected to rise by more than 50 percent over the next 25 years (Bruinsma, 2003). Also
international trade in feed is growing. As a result of the increasing global trade in feed crops and animal
products and the growth of meat preservation over longer periods, many consumers have no longer any idea
about the natural resource use and environmental impacts associated with the products they consume.
Consumers of animal products are spatially disconnected from the processes necessary to produce the products
(Naylor et al., 2005; Hoekstra, 2010). The concept of ‘water footprint’ provides an appropriate framework of
analysis to find the link between the consumption of animal products and the use of the global water resources.
The water footprint is defined as the total volume of freshwater that is used to produce the goods and services
consumed by an individual or community (Hoekstra and Chapagain, 2008).
8 / The water footprint of farm animals and animal products
There are a few earlier publications on water use in animal production. The first and most comprehensive
assessment of the water footprint of farm animals and animal products was carried out by Chapagain and
Hoekstra (2003) and later updated by the same authors in their water footprint of nation’s publication
(Chapagain and Hoekstra, 2004). A study by FAO has quantified the global blue water use for feed production,
animal drinking and servicing (Steinfeld et al., 2006). De Fraiture et al. (2007) have estimated the global water
use for animal feed production, both green and blue but not distinguishing between the two. They considered
water use for two lumped categories: feed crops and grazing. Zimmer and Renault (2003) made a rough
estimation of the global water consumption for producing meat and other animal products, not showing details
per country, animal category or product. Galloway et al. (2007) produced a study on the water consumption for
chicken and pig for four countries: the USA, Japan, Brazil and the Netherlands. Peden et al. (2007) made an
estimate of the global water consumption for producing the feed for farm animals. In addition to the studies
mentioned there have been a few more specific studies for the Nile River Basin (Van Breugel et al., 2010) and
for the USA (Renault and Wallender, 2000; Pimentel et al., 2004).
With the exception of Chapagain and Hoekstra (2003, 2004), none of the studies have estimated the water
footprint of animal products by product and country at a global level. Although Chapagain and Hoekstra (2003,
2004) were able to estimate the water footprint of farm animals and animal products per country, they have
taken a very crude assumption on the composition and amount of feed consumed by the different animals.
Besides, the water footprints of feed crops were estimated based on national average climatic data. We have
tried to improve the estimation of feed composition and feed amount per animal category and have used better
estimates for the water footprints of feed crops.
The objective of the study is to assess the water footprint of farm animals and the various derived animal
products for the period 1996-2005. We consider eight animal categories: beef and dairy cattle, pig, sheep, goat,
broiler and layer chicken and horses. The main differences with Chapagain and Hoekstra (2003, 2004) are:

We have estimated the amount of feed consumed per animal category, per production system and per
country based on estimates of feed conversion efficiencies and statistics on the annual production of animal
products. Chapagain and Hoekstra (2003, 2004) have taken rough assumptions on the quantities of feed
consumed per animal category based on incidental data.

We reckon with the relative occurrence of the three production systems (grazing, mixed and industrial) in
each country, using the studies of Seré and Steinfeld (1996) and Wint and Robinson (2007). In Chapagain
and Hoekstra (2003, 2004), for each country the dominant animal production system was selected, after
which further calculations for this country were based on data for that specific production system.

We have estimated the green, blue and grey water footprints of the feed crops using a spatially explicit crop
water use model able to estimate actual crop water use (Mekonnen and Hoekstra, 2010a, 2010b). In the
previous studies the potential rather than the actual crop water use was used. In addition, the estimate was
based on country average climatic data which could lead to errors in large countries. Furthermore the earlier
studies did not explicitly distinguish between the green and blue water footprint components and did not
include the grey water footprint component at all.
2. Method and data
2.1
Method
We follow the water footprint definitions and methodology as set out in Hoekstra et al. (2009). The blue water
footprint refers to consumption of blue water resources (surface and groundwater) along the supply chain of a
product. ‘Consumption’ refers to loss of water from the available ground-surface water body in a catchment area.
Losses occur when water evaporates, returns to another catchment area or the sea or is incorporated into a
product. The green water footprint refers to consumption of green water resources (rainwater in so far as it does
not become run-off). The grey water footprint refers to pollution and is defined as the volume of freshwater that
is required to assimilate the load of pollutants given natural background concentrations and existing ambient
water quality standards.
We consider eight farm animal categories: beef and dairy cattle, pig, sheep, goat, broiler and layer chicken and
horses. When estimating total feed amounts and total water footprints per category, we include ‘buffaloes’ in the
category of ‘beef cattle’ and ‘asses and mules’ in the category of ‘horses’.
The water footprint of a live animal consists of different components: the indirect water footprint of the feed and
the direct water footprint related to the drinking water and service water consumed (Chapagain and Hoekstra,
2003, 2004). The water footprint of an animal is expressed as:
WF [a, c, s ]  WF feed [a, c, s ]  WFdrink [a, c, s ]  WFserv [a, c, s ]
(1)
where WFfeed[a,c,s], WFdrink[a,c,s] and WFserv[a,c,s] represent the water footprint of an animal for animal
category a in country c in production systems s related to feed, drinking water and service water consumption,
respectively. Service water refers to the water used to clean the farmyard, wash the animal and carry out other
services necessary to maintain the environment. The water footprint of an animal and its three components can
be expressed in terms of m3/yr/animal, or, when summed over the lifetime of the animal, in terms of m3/animal.
For beef cattle, pig, sheep, goat and broiler chicken – animals that provide their products after they have been
slaughtered – it is most useful to look at the water footprint of the animal at the end of its lifetime, because it is
this total that will be allocated to the various products (e.g. meat, leather). For dairy cattle and layer chicken, it is
most straightforward to look at the water footprint of the animal per year (averaged over its lifetime), because
one can easily relate this annual animal water footprint to its average annual production (milk, eggs).
The water footprint of an animal related to the feed consumed consists of two parts: the water footprint of the
various feed ingredients and the water that is used to mix the feed:
 Feed[a, c, s, p]  WF
n
WF feed [a, c, s ] 
 WF

prod [ p ]
p 1
Pop [a, c, s ]
mixing [ a, c, s ]
(2)
10 / The water footprint of farm animals and animal products
Feed[a,c,s,p] represents the annual amount of feed ingredient p consumed by animal category a in country c and

production system s (ton/yr), WFprod
[ p ] the water footprint of feed ingredient p (m3/ton), WFmixing[a,c,s] the
volume of water consumed for mixing the feed for animal category a in country c and production system s
(m3/yr/animal) and Pop*[a,c,s] the number of slaughtered animals per year or the number of milk or egg
producing animals in a year for animal category a in country c and production system s.
The water footprint of feed ingredients

The water footprints of the different crops, roughages and crop by-products ( WFprod
[ p] , m3/ton) that are eaten
by the various farm animals have been calculated following the methodology developed by Hoekstra and
Chapagain (2008) and Hoekstra et al. (2009). The water footprints of feed crops were estimated using a crop
water use model that estimates crop water footprints at a 5 by 5 arc minute spatial resolution globally (Mekonnen
and Hoekstra, 2010a, 2010b). Grey water footprints were estimated by looking at leaching and runoff of nitrogen
fertilisers only, following Mekonnen and Hoekstra (2010a,b). Since animal feed in a country originates from
domestic production and imported products, for the calculation of the water footprint of animal feed in a country,
we have taken a weighted average water footprint according to the relative volumes of domestic production and
import:
 T [n ,p]  WF
P[ p ]   T [n ,p]
P[ p]  WFprod [ p] 

WFprod
[ p] 
i
e

prod [ ne ,p ]
ne
i
(3)
e
ne
in which P[p] is the production quantity of feed product p in a country (ton/yr), Ti[ne,p] the imported quantity of
feed product p from exporting nation ne (ton/yr), WFprod[p] the water footprint of feed product p when produced
in the nation considered (m3/ton) and WFprod[ne,p] the water footprint of feed product p as in the exporting nation
ne (m3/ton). The water footprint of crop residues such as bran, straw, chaff and leaves and tops from sugar beet
have already been accounted for in the main product, therefore their water footprint was set equal to zero.
Volume and composition of feed
The volume and composition of the feed consumed vary depending on the type of animal, the production system
and the country. The amount of feed consumed is estimated following the approach of Hendy et al. (1995), in
which the total annual feed consumption (including both concentrates and roughages) is calculated based on
annual production of animal products and feed conversion efficiencies. Only for horses we have used the
approach as in Chapagain and Hoekstra (2003), which means that we multiplied the estimated feed consumption
per animal by the number of animals, thus arriving at an estimate of the total feed consumed by horses.
The steps followed to calculate the volumes and composition of feed are schematically shown in Figure 1. The
total feed per production system for both ruminants and non-ruminants animals is calculated as follows:
Feed [a, c, s ]  FCE[a, c, s ]  P[a, c, s ]
(4)
The water footprint of farm animals and animal products / 11
where Feed[a,c,s] is the total amount of feed consumed by animal category a (ton/yr) in country c and
production system s, FCE[a,c,s] the feed conversion efficiency (kg dry mass of feed / kg of product) for animal
category a in country c and production system s, and P[a,c,s] the total amount of product (meat, milk, or egg)
produced by animal category a (ton/yr) in country c and production system s.
For ruminants
Animal live weight
LW[a,c,s]
Daily feed intake
rate
FIR[a,c,s]
Per capita annual
feed intake FI[a,c,s]
Annual animal
products output
P[a,c,s]
Total animal
population
Pop[a,c,s]
Per capita products
output PO[a,c,s]
Directly available for
non-ruminants
Average feed
conversion efficiency
FCE[a,c,s]
Annual animal
products output
P[a,c,s]
Total feed
Feed[a,c,s]
Roughage feed
Roughage[a,c,s]
Concentrate feed
Concentrate[a,c,s]
Share of
concentrate out of
total feed fc[a,c,s]
FAOSTAT Concentrate
feed per crop per country
Concentrate[p,c]
Concentrate feed
per crop
Concentrate[a,c,s,p]
Concentrate composition in terms
of major categories per animal
according to Wheeler et al. (1981)
Figure 1. Steps in the calculation of feed amount per animal. For ruminants (beef cattle, dairy cattle, sheep and
goat), feed conversion efficiencies are derived as indicated in the upper part of the scheme. For non-ruminants
(pig, broiler and layer chicken), the feed conversion efficiencies are directly taken from the literature.
Estimating feed conversion efficiencies
Feed conversion efficiency is defined as the amount of feed consumed per unit of produced animal product (e.g.
meat, milk, egg). Feed conversion efficiencies were estimated separately for each animal category (beef cattle,
dairy cattle, sheep, goat, pig, broiler chicken and egg layer chicken), for each animal production system and per
country. Although the term used may suggest precisely the opposite, animals that have a low ‘feed conversion
efficiency’ are efficient users of feed. We use the term here as generally used in livestock studies. The feed
conversion efficiencies (FCE, kg dry mass/kg product) for non-ruminants (pig and chicken) were adopted from
Hendy et al. (1995). For ruminants (cattle, goat, sheep), feed conversion efficiencies were estimated through
dividing feed intake per capita by annual production (of beef, milk, sheep and goat meat) per capita:
12 / The water footprint of farm animals and animal products
FCE[a, c, s ] 
FI [a, c, s ]
PO[a, c, s ]
(5)
where FI[a,c,s] is the feed intake per head by ruminant animal category a in country c and production system s
(kg dry mass/yr/animal), and PO[a,c,s] the product output per head for ruminant animal category a in country c
and production system s (kg product/yr/animal). The product output (beef, milk, sheep and goat meat) per animal
for ruminants is calculated as:
PO[a, c, s ] 
P[a, c, s ]
Pop[a, c, s ]
(6)
in which P[a,c,s] is the total annual production of beef, milk, sheep meat or goat meat in country c in production
system s (kg/yr) and Pop[a,c,s] the total population of beef cattle, dairy cattle, sheep or goat in that country and
production system.
Estimating the total annual production of animal products
The annual production of animal products has been estimated as shown in Figure 2. The meat production (Pmeat,
ton/yr) per animal category a (beef cattle, pig, sheep and goat) in country c and production system s is estimated
by multiplying the carcass yield per slaughtered animal by the annual number of animals slaughtered:
Pmeat [a, c, s ]  CY [a, c, s ]  SA[a, c, s ]
(7)
The carcass yield (CY, kg/animal) for each animal category per production system was estimated by combining
country average carcass yield data from FAO (2009) with data on animal live weight per production system per
economic region (Hendy et al. 1995) and data on carcass weight as percentage of live weight (FAO, 2003). The
obtained carcass yields were scaled such that the total meat production per animal category equals the value
provided by FAO (2009). The number of slaughtered animals per production system (SA, number of animal/yr)
was calculated by multiplying the total animal number by the animal off-take rate per production system:
SA[a, c, s ]  Pop[a, c, s ]  OR[a, c, s ]
(8)
where Pop[a,c,s] is the population of animal category a in country c for production system s and OR[a,c,s] the
off-take rate, which is the fraction of the animal population that is taken out in a given year for slaughter
(dimensionless).
Milk and egg production per production system and country were calculated as:
Pmilk [a, c, s ]  MY [a, c, s ]  DC[a, c, s ]
Pegg [a, c, s ]  f egg [a, c, s ]  Pegg [a, c]
(9)
(10)
The water footprint of farm animals and animal products / 13
where Pmilk[a,c,s] and Pegg[a,c,s] represent production of milk and egg in country c and production system s
respectively (ton/yr), MY[a,c,s] milk yield per dairy cow in country c and production system s (ton/dairy cow),
DC[a,c,s] the number of dairy cows in country c and production system s, fegg[a,c,s] the fraction of egg produced
in country c and production system s and Pegg[a,c] the total amount of egg produced in country c (ton/yr).
Fraction of animal per
country per production
system
fa[a,c,s]
Carcass weight as
percent of live weight per
country fcw[a,c]
Animal per country
Pop[a,c]
Animal per country per
production system
Pop[a,c,s]
Animal off-take rate
per country
OR[a,c]
Animal off-take rate per
country per production
system
OR[a,c,s]
Carcass yield per
country per production
system CY[a,c,s]
Carcass yield per country
CY[a,c]
Number of
slaughtered animal
per country SA[a,c]
Number of slaughtered
animals per country per
production system
SA[a,c,s]
Meat production per
production system per
country Pmeat[a,c,s]
National average meat
production per country
Pmeat[a,c]
Animal live weight per
country per production
system LW[a,c,s]
(a) Meat production per production system and per country
Milk yield per
production
system MY[a,s]
Fraction of milk
produced per
production
system fmilk[a,s]
Milk yield per
country MY[a,c]
Dairy cow number
per country
Popdiary[a,c]
Milk yield per
country per
production system
MY[a,c,s]
Dairy cow number
per country per
system
Popdiary[a,c,s]
Milk production
per country
Pmilk[a,c]
Milk production per
country per
production system
Pmilk[a,c,s]
(b) Milk production and yield per country per production system
Egg production
per country
Pegg[a,c]
Fraction of egg
produced per
system fegg[a,s]
Egg production
per country per
system
Pegg[a,c,s]
(c) Egg production per country and per production system
Figure 2. Steps in the calculation of: (a) annual meat production (beef cattle, pig, sheep, goat, broiler chicken); (b)
annual milk production (dairy cattle); and (c) annual egg production (layer chicken). Broken arrows indicate
iteration and adjustment to fit to values of FAO (2009).
Estimating the feed composition
Animal feeds are generally divided into ‘concentrates’ and ‘roughages’ (Box 2.1). The volume of concentrate
feed has been estimated per animal category and per production system as:
Concentrate[a, c, s ]  Feed[a, c, s ]  f c [a, c, s ]
(11)
where Concentrate[a,c,s] is the volume of concentrate feed consumed by animal category a in country c and
production system s (ton/yr) and fc[a,c,s] the fraction of concentrate in the total feed for animal category a in
country c and production system s. For the latter variable, data have been obtained from Hendy et al. (1995) and
Bouwman et al. (2005).
14 / The water footprint of farm animals and animal products
The composition of concentrate feeds varies across animal species and regions of the world. To our knowledge,
there are no datasets with global coverage on the composition of feed for the different animals per country.
Therefore, we have made a number of assumptions concerning the concentrate feed composition of the different
animal species. According to Hendy et al. (1995), the diets of pig and poultry include, on average, 50-60%
cereals, 10-20% oil meals and 15-25% ‘other concentrates’ (grain substitutes, milling by-products, nonconventional concentrates). Wheeler et al. (1981) provide the feed composition in terms of major crop categories
for the different animal categories (Figure 3 and Figure 4). We have used these and other sources in combination
with FAOSTAT country average concentrate feed values for the period 1996-2003 (FAO, 2009) to estimate the
diet composition of the different animal species. In order to estimate the feed in terms of specific crops per
animal, we first estimated the feed in terms of major crop categories following Wheeler et al. (1981). The feed in
terms of major crop categories is further distributed to each crop proportional to the crop’s share in its crops
category as obtained from FAOSTAT (FAO, 2009). The roughage feed is divided into fodder, grass and crop
residues using the data obtained from Bouwman et al. (2005).
Box 2.1 Definition of feed components. Source: Hendy et al. (1995) and FAO(1983).
Feeds are generally divided into ‘concentrates’ and ‘roughages’.

Concentrates are feeds which contain a high level of nutrients for a given weight of feed usually low in crude fibre content (less than
18% of dry matter content) and high in total digestible nutrients. Thus concentrates may be high in energy, as in the case of cereals
and milling by-products or they may be high in protein, as are protein meals of either vegetable or animal origin. The concentrates
considered in this study include all the feed material found in FAO (2009) and which are derived from crops. The concentrate feeds
considered include cereals, roots and tubers, oil crops, oil meals, bran, molasses, pulses, sugar crops, fruits and vegetables.

Roughages are feeds with low density of nutrients, with a crude fibre content over 18% of dry matter, include most fresh and dried
forages and fodders. The main roughages are:
o pastures: includes temporary and permanent pastures.
o harvested roughages: include those which are sown and harvested annually for forage, fodder or silage. The principal types of
harvest roughages include forage (green) cereals such as maize, oats and sweet sorghum; sugarcane, lucerne (alfalfa) and berseem
(Egyptian clover); special high yielding grasses cultivated chiefly for silage (such as Thimoth grass); roots and tubers such as
potatoes, beets, swedes, turnips; oilseeds such as winter rape; pulses such as field peas, beans, sweet lupins and vetches;
vegetables such as pumpkins and cabbages. These feeds are sometimes processed for lower fibre content and bulk and are then
usually classified as concentrate feeds (e.g. cassava chips and pellets, processed alfalfa, pea and bean meals).
o other roughages: include a large variety of crop by-products such as straw and chaff from cereals and pulses; leaves and tops from
sugar beet; fodder beets and vegetables; and other miscellaneous roughages such as acacia and ipil ipil (leucaena) leaves.
2.2
Data
A large amount of data has been collected from different sources. A major data source for animal stocks,
numbers of animals slaughtered each year, annual production of animal products, and concentrate feed per
country is FAOSTAT (FAO, 2009). Other important sources that have been used are: Seré and Steinfeld (1996),
Hendy et al. (1995), Bouwman et al. (2005), Wint and Robinson (2007), Wheeler et al. (1981) and FAO (2003).
Box 2.2 summarizes how specific data have been obtained from these different sources.
The water footprint of farm animals and animal products / 15
Box 2.2. Overview of data sources.

Animal production systems: Seré and Steinfeld (1996) have developed a classification of animal production systems based on agroecology, the distinction between pastoral, mixed and landless systems and on the presence of irrigation or not. They distinguish
eleven animal production systems grouped under three headings: grazing (extensive), mixed and industrial (intensive). In this study
we use the schematization into these three production systems.

Feed conversion efficiencies: For ruminants, the feed conversion efficiencies were estimated as explained in Section 2.1. For nonruminants (pig, broiler and egg laying chicken), feed conversion efficiencies per animal category, per production system and per
economic region were obtained from Hendy et al. (1995). For both ruminants and non-ruminants, the feed conversion efficiency data
were scaled such that at the level of world regions they match the efficiencies as reported in Bouwman et al. (2005).

Annual production of animal products: Data on the annual production of animal products (beef, pig meat, sheep meat, goat meat,
chicken meat, milk and egg) per production system for different economic regions were obtained from Seré and Steinfeld (1996).
Production data per product and country for the period 1996-2005 were obtained from FAOSTAT (FAO, 2009). The two data
sources have been combined to derive production data per animal category, production system and per country for the period 19962005. We scaled the production data per production system such that at national level, the production aggregated over the different
production systems equals the production as reported in FAO (2009) for the period 1996-2005.

Number of animals: Seré and Steinfeld (1996) provide the total animal population for the different production systems for the year
1995 for a number of geographic regions in the world. Wint and Robinson (2007) provide the total animal population for the year
2005 for the different production systems for developing countries. We have combined the two sources to obtain number of animals
per animal category, per production system and per country. We scaled the numbers such that at national level, the number of animals
aggregated over the different production systems equal the numbers as reported in FAO (2009) for the period 1996-2005.

Number of slaughtered animals and animal off-take rates: The annual number of slaughtered animals for beef cattle, pig, sheep,
goat and broiler chicken per country have been taken from FAO (2009). The animal off-take rates at national level have been derived
from the same source by dividing the annual number of slaughtered animals by the total population. The off-take rate for the grazing
system was assumed to be 90% of the national average off-take rate for the animal category considered (Bouwman, et al., 2005). Per
country, the off-take rate for the mixed and industrial production systems were scaled until the total number of slaughtered animals
per animal category equalled the value provided by FAO (2009).

Animal live weight: Hendy et al. (1995) provide live weight of ruminant animals (beef cattle, dairy cattle, sheep and goat) by
production system and economic region. FAO (2003) give animal live weight for cattle, pig, sheep, goat and chicken. We combined
these two sources, taking advantage of the fact that Hendy et al. (1995) specify data per production system (but not per country) and
FAO (2003) provides data per country (but not per system).

Carcass weight as percentage of live weight: FAO (2003) provides carcass weight as percentage of live weight for the different
animal categories per country.

Ruminant animals daily feed intake rate: Daily feed intake rate for ruminant animals (beef cattle, dairy cattle, sheep and goat) was
obtained from Hendy et al. (1995).

Share of concentrate feed in total animal feed: The contribution of concentrate feeds such as cereals, oil-meals, roots and other
crop products in the total feed composition was obtained from Hendy et al. (1995) and Bouwman et al. (2005).

Composition of the concentrate feed: The composition of concentrate feed per animal category was estimated following mainly
Wheeler et al. (1981) (Figure 3-4). In addition, we used Steinfeld et al. (2006) for data on the relative composition of poultry and pig
feed for major countries (Figure 5-6). The data available in Wheeler et al. (1981) and Steinfeld et al. (2006) are not sufficient to
specify the feed composition at the level of specific crops or crop products. In order to come to that level of detail we use the Supply
and Utilization Accounts of FAOSTAT (FAO, 2009), which provide the total concentrate feed utilization per country per crop and
crop product.

Composition of the roughage feed: We used Bouwman et al. (2005) to estimate the composition of the roughage feed (grass, fodder
crops, crop residues).

Water use for drinking and animal servicing: Data were obtained from Chapagain and Hoekstra (2003). See Appendix IV.

Water use for mixing feed: Following Chapagain and Hoekstra (2003), the water use for feed mixing is assumed to be 50% of total
concentrate feed intake (or 0.5 litre per kg of concentrate feed intake).
16 / The water footprint of farm animals and animal products
Average feed utilization (%)
80
60
40
20
0
Cereals
Oilmeals
Cattle and buffaloes
Other concentrates
Sheep and goats
Pigs
Roughages
Poultry
Total feed
Other
Figure 3. World average utilization of feeds by different animal species in metabolisable energy equivalents
Source: Wheeler et al. (1981).
Composition of diet (%)
100
80
60
40
20
0
Cattle and
buffaloes
Sheep and goats
Cereals
Oilmeals
Pigs
Poultry
Other concentrates
Roughages
Others
Figure 4. Aggregate world composition of diets for different species of animal in metabolisable energy equivalents
Source: Wheeler et al. (1981).
The water footprint of farm animals and animal products / 17
100
90
Feed composition (%)
80
70
60
50
40
30
20
10
0
Barley
Maize
Sorghum
Wheat
Peas
Soybean Cake
Other oilmeals
Fish meal
Others
Figure 5. Relative composition of poultry feed basket in selected countries (by weight). Source: Steinfeld et al.
(2006).
100
90
Feed composition (%)
80
70
60
50
40
30
20
10
0
Barley
Maize
Rice
Rye
Sorghum
Wheat
Peas
Soybean Cake
Rapeseed Cake
Fish meal
Others
Figure 6. Relative composition of pig feed basket in selected countries (by weight). Source: Steinfeld et al. (2006).
3. Results
3.1
Quantity and composition of animal feed
Table 1 provides global average feed conversion efficiencies for different animal categories and production
systems. Region-specific feed conversion efficiencies are presented in Appendix I. Ruminants (cattle, sheep,
goat) are less efficient in converting feed into meat than non-ruminants (pig, chicken), amongst other due to the
lower quality of feed they consume. Particularly meat production from cattle costs a lot of feed per unit of
product obtained. Although ruminants need more feed, their feed largely consists of forage and other materials
that humans cannot eat, while non-ruminants consume large amounts of concentrate feed that could be used for
human consumption. Non-ruminants thus most obviously compete with humans for food, but in an indirect way
ruminants also compete for food with humans. In some cases the roughages eaten by ruminants are produced
with land and water resources that cannot alternatively be allocated to crop production for human consumption
(e.g. in the case of grazing in dry or wetlands), but often the land and water resources used for roughages supply
can alternatively be used for crop growth for human consumption, so that ruminants compete with humans for
food also through consumption of roughages.
Table 1. Global average feed conversion efficiency per animal category and production system.
Feed conversion efficiency (kg dry mass feed/kg output)
Animal category
Grazing
Mixed
Industrial
Overall
Beef cattle
70.1
51.8
19.2
46.9
Dairy cattle
3.5
1.6
1.1
1.9
Broiler chicken
9.0
4.9
2.8
4.2
Layer chicken
9.3
4.4
2.3
3.1
Pig
11.3
6.5
3.9
5.8
Sheep and goat
49.6
25.8
13.3
30.2
Non-ruminants are responsible for 60% of the global consumption of concentrate feeds; ruminants account for
40%. Figure 7 shows the consumption of different concentrates by different animal categories. Chickens take the
largest share in total concentrate feed consumption (30%). Three fifth of the concentrate feed consumption by
chicken in the world is for broiler chicken and two fifth for layer chicken. Pig meat production takes nearly the
same share (29%) in global concentrate feed consumption, while dairy cattle are responsible for 25% and beef
cattle 14%. Our estimated shares of different animal categories in the total concentrate feed consumption is very
close to the estimates made by Hendy et al. (1995).
Annual concentrate feed consumption averaged over the period 1996-2005 expressed in commodity fresh weight
amounted to 1195 million tons per year. This value is very close to the feed data provided by FAO (2009) for the
period 1996-2003 (1229 million ton/yr). The feed data analysed and presented here focus on commodities
derived from crop production. Figure 8 presents a summary of the global total feed utilization of cereals, oil
meals and cakes, roots and tubers, bran and others. Cereals make up the largest percentage of the total
concentrate feed use (57%), followed by oil meals (15%), roots (11%) and brans (10%).
20 / The water footprint of farm animals and animal products
Consumption of different concentrates
(Million ton/yr)
400
Others
300
Oilmeals
Molases
Brans
200
Sugar crops
Roots
100
Pulses
Oil crops
Cereals
0
Sheep &
goat
Layer
chicken
Beef cattle
Broiler
chicken
Dairy
Pig
Figure 7. Consumption of different concentrates per animal category.
Oil crops
1%
Cereals
57%
Pulses
1%
Roots 11%
Sugar crops
2%
Brans
10%
Molases
1%
Others
2%
Oilmeals
15%
Figure 8. Contribution of different crops (on fresh weight basis) toward global total concentrate feed utilization.
Period 1996-2005.
The estimated global amount of feed consumption per animal category and world region is presented in
Appendix II. Feed consumption per production system is shown in Appendix III. The total feed consumption
over the period 1996-2005 was 4996 million ton feed in dry matter per year, on average. Roughages account for
the largest share out of this total, accounting for 80%, and feeds derived from crop production account for the
remaining 20%. Considering only plant-based feed materials, our global estimate of total feed in dry matter
The water footprint of farm animals and animal products / 21
(4996 Mton dry mass/yr) is about 6% lower than the estimate of Wirsenius (2000) (5300 Mton dry mass/yr) and
8% more than the estimate of Bouwman et al. (2005) for 1995 (4637 Mton dry mass/yr). Our estimate of global
utilization of roughages (4010 Mton dry mass/yr), which includes pasture, forages, straws, sugar crops tops and
leaves, oil crops stalks and husks is 15% lower than the estimate of Wirsenius (2000) (4740 Mton dry mass/yr)
and 5% larger than the estimate of Bouwman et al. (2005) for 1995 (3832 Mton dry mass/yr).
3.2
The water footprint of animal feed
The water footprint per ton of feed differs among crops and across countries. Since the most significant part of
the animal water footprint comes from the feed they consume, the water footprint per unit of feed is an important
factor in the determination of the water footprint of animals and their associated derived products. Table 2 shows
the average water footprint of selected feed ingredients for selected countries. Crop residues and by-products
such as bran, straw, chaff and leaves and tops from sugar beet have a water footprint of about zero, because the
water footprint of crop growing is mainly attributed to the main crop products, not the low-value residues or byproducts. As a result they provide an opportunity to reduce the water footprint of animal production. Huge
reduction in the water footprint of animals can also be obtained by using crops with a relatively low water
footprint per ton such as sugar beet. Therefore, careful selection of feeds that meet the nutrient requirement of the
animals and at the same time have a smaller water footprint per ton could significantly reduce the indirect use of
freshwater resources associated with animal production.
3.3
The water footprint of live animals at the end of their lifetime and animal products per ton
Table 3 shows, for each animal category, the average water footprint of an animal at the end of its life time and
the annual water footprint of an animal. Dairy cows have the largest annual water footprint (2056 m3/yr/animal),
which is more than the average human being. Broiler chicken have the smallest footprint (26 m3/yr/animal).
Table 4 presents the green, blue and grey water footprints of some selected animal products per production
system for selected countries. Appendix V presents the full result of our analysis: green, blue and grey water
footprints of all farm animals and animal products considered, per production system and per country. The water
footprints of animals and animal products vary greatly across countries and production systems. When we look at
global averages, however, we see that the water footprint of meat increases from chicken meat (4300 m3/ton),
goat meat (5500 m3/ton), pig meat (6000 m3/ton), sheep meat (10400 m3/ton) to beef (15400 m3/ton). The
differences can be partly explained from the different feed conversion efficiencies of the animals. Beef
production, for example, requires eight times more feed (in dry matter) per kilogram of meat compared to
producing pig meat, and eleven times if compared to the case of chicken meat. This is not the only factor,
however, that can explain the differences. Another important factor is the feed composition. Particularly the
fraction of concentrate feed in the total feed is important, because concentrate feed generally has a larger water
footprint than roughages. Chicken, which are efficient from a total feed point of view, are no longer that efficient
when we look at the fraction of concentrates in their feed. This fraction is 73% for broiler chicken (global
average), while it is only 5% for beef cattle.
22 / The water footprint of farm animals and animal products
Blue
17
9
455
590
Grey
102
129
308
316
Green
1638
1411
847
666
7
20
1591
Blue
Maize
Millet
Soybeans
Rapeseed
Fodder crops
Pasture
1842
1277
1162
318
88
342
178
294
203
227
207
499
1247
941
908
1213
780
376
204
79
145
861
194
96
120
145
131
Green
718
1619
791
311
440
2225
1490
523
947
Blue
521
1
74
713
20
103
62
63
81
Grey
135
124
295
364
118
195
308
176
194
Green
2954
3344
1600
11982
2509
3719
2953
2990
4306
164
40
26
84
76
59
61
57
Grey
228
141
222
79
128
233
302
309
115
Green
444
433
357
422
394
258
529
471
550
1
Grey
32
17
56
31
29
24
22
22
13
Green
116
39
147
14
60
63
49
67
82
Blue
3
59
164
3
26
37
26
Grey
63
12
82
50
21
29
14
20
25
1714
2186
2231
1869
1533
3322
1629
1562
2037
Blue
65
1
129
122
23
18
98
92
70
Grey
10
15
106
43
11
92
10
10
37
2095
2771
1483
1556
1155
1646
2567
2743
1703
2
7
1213
1
1467
4
3
231
420
98
466
197
259
235
341
360
336
1422
1813
1851
1550
1272
2756
1352
1296
1690
Blue
54
1
107
101
19
15
81
76
58
Grey
8
12
88
35
9
76
8
8
31
Green
254
648
328
154
245
1170
425
388
471
Blue
276
52
111
670
178
341
195
169
270
Grey
53
81
114
103
53
172
48
68
91
Green
254
158
2461
232
131
412
117
244
207
Blue
204
148
33
44
27
Grey
15
7
105
285
30
31
11
35
20
Green
762
307
225
225
131
407
174
372
315
Green
Green
Grey
Cottonseed Cake
1021
139
Blue
Sesame seed
Cake
643
155
Blue
Sugar beet
608
Grey
Blue
Cassava
World
Average
784
USA
839
Brazil
1850
Mexico
Barley
1994
India
Green
Germany
Wheat
Egypt
Water
footprint
component
China
Feed
Australia
Table 2. Average water footprint of selected feed components for selected countries (m3/ton) (1996-2005).
Green
Blue
Grey
Source: data for feed crops based on Mekonnen and Hoekstra (2010b); data for pasture from this study. The
water footprints shown in this table refer the weighted average of domestically produced and imported feeds.
The water footprint of farm animals and animal products / 23
Table 3. Average annual water footprint of one animal, per animal category (1996-2005).
Animal
category
Water footprint
of live animal at
end of life time
(m3/ton)
Average animal
weight at end of
life time (kg)
Dairy cattle
Horse
Average water
footprint at end of
3
life time (m /animal)
Average annual
Average life
water footprint of one
time (yr)
animal (m3/yr/animal)
20558
10
2056
40612
473
19189
12
1599
Beef cattle
7477
253
1889
3.0
630
Pig
3831
102
390
0.75
520
Sheep
4519
31.3
141
2.1
68
47
1.4
33
Layer chicken
Goat
3079
24.6
76
2.3
32
Broiler chicken
3364
1.90
6
0.25
26
Total water footprint per ton of product
For all farm animal products, except dairy products, the total water footprint per unit of product declines from the
grazing to the mixed production system and then again from the mixed to the industrial production system. The
reason is that, when moving from grazing to industrial production systems, feed conversion efficiencies become
better. Per unit of product, about three to four times more feed is required for grazing systems when compared to
industrial systems (see Table 1). More feed implies that more water is needed to produce the feed. However, the
fact that feed conversion efficiencies in grazing and industrial production systems differ by a factor 3 to 4 does
not mean that the water footprints of animal products are 3 to 4 times larger when derived from a grazing instead
of an industrial system. This is because the feed composition of animals raised in grazing systems is generally
more favourable from a water resources point of view. For all animal categories, the fraction of concentrate feed
in the total feed is larger for industrial systems if compared to mixed production systems and larger for mixed
systems if compared to grazing systems. The water footprint per kg of concentrate feed is generally larger than
for roughages, so that this works to the disadvantage of the total water footprint of animals raised in industrial
systems and to the advantage of the total water footprint of animals raised in grazing systems. This effect,
however, does not fully compensate for the unfavourable feed conversion efficiencies in grazing systems. An
exception is in dairy farming, where the total water footprint per unit of product is comparable in all three
production systems. For dairy products, the water footprint happens to be smallest when they are derived from a
mixed system and a bit larger but comparable when obtained from a grazing or industrial system.
Blue and grey water footprints per ton of product
All the above is about comparing the total water footprints of animal products. The picture changes when we
focus on the blue and grey water footprint components. With the exception of chicken products, blue and grey
water footprints always increase from grazing to industrial production systems. Figure 9 illustrates this by
showing the blue water footprint of a number of animal products across the three productions systems. For the
grey water footprint similar pictures can be obtained. The larger blue and grey water footprints for products
obtained from industrial production systems are caused by the fact that concentrate feed takes a larger share in
the total feed in industrial systems when compared to grazing systems. For beef cattle in grazing systems, the
24 / The water footprint of farm animals and animal products
global average share of concentrate feed in total feed is 2%, while in industrial systems it is 21%. Mixed systems
are generally somewhere in between. Although the feed crops that are contained in the concentrate feed are often
to a great extent based on green water, there is a blue water footprint component as well, and the larger the
consumption of feed crops compared to roughages, the larger the total amount of blue water consumed. This
explains the larger blue water footprint per ton of product in industrial production systems for beef, milk, cheese,
and pig, sheep and goat meat. The application and leaching of fertilizers and other agro-chemicals in feed crop
production results in the fact that the grey water footprint of animal products from industrial systems, where the
dependence on feed crops is greatest, is larger than for grazing systems. Given the fact that freshwater problems
generally relate to blue water scarcity and water pollution and to a lesser extent to competition over green water,
this means that – from a water resources point of view – grazing systems are preferable over industrial
production systems for cattle, pig, sheep and goat.
In the case of chicken products (chicken meat and egg), the industrial production system has, on average, a
smaller blue and grey water footprint per ton of product compared to the other two production systems. The
reason is that chicken strongly rely on concentrate feed in all production systems, intensive or extensive. Broiler
chicken in extensive systems have a share of concentrate feed in total feed of 63%, while this is 81% in intensive
industrial systems. There is still a difference, but the differences in feed composition for both broiler and layer
chicken is less outspoken if compared to the other animal categories. As a result, the relatively unfavourable feed
conversion efficiency in extensive systems is not compensated by a more favourable composition of the feed as
is the case in the other animal categories.
Country differences
In general terms, one can say that the type of production system is highly relevant for the size, composition and
geographic spread of the water footprint of an animal product, because the type of production system determines
feed conversion efficiency, feed composition and origin of feed. Similarly we observe that the country of
production influences the water footprint of animal products in general terms as well. The Netherlands, for
example, shows lower total water footprints for most animal products if compared to the USA. The USA, in turn,
generally shows lower total water footprints for animal products than India. These crude general differences
between countries are related to existing country differences in feed conversion efficiencies, but also to the fact
that water footprints of feed crops vary across countries as a function of differences in climate and agricultural
practice.
Water footprint components - example for beef
For all animal products, the water footprint related to the animal feed takes by far the largest share in the total
water footprint. Further one can say that the green water footprint is always much larger than the blue and grey
water footprints. As an example, Table 5 shows in detail the components of the water footprint of producing a
kilogram of beef. The water footprint is dominantly green water (94%) and the largest share comes from the feed
the cattle consume (99%). Drinking and service water contribute only 1% toward the total water footprint, but
30% to the blue water footprint. The major fraction (83%) of the water footprint of a beef cow is attributed to the
derived beef, but smaller fractions go to the other products: offal, leather and semen.
Table 4. The green, blue and grey water footprint of selected animal products for selected countries (m3/ton).
Animal
products
Beef
Australia
Brazil
China
India
Netherlands
Russia
USA
Global average
Farming system
Grazing
Mixed
Industrial
Weighted average
Sheep meat Grazing
Mixed
Industrial
Weighted average
Goat meat
Grazing
Mixed
Industrial
Weighted average
Pig meat
Grazing
Mixed
Industrial
Weighted average
Chicken
Grazing
meat
Mixed
Industrial
Weighted average
Egg
Grazing
Mixed
Industrial
Weighted average
Milk
Grazing
Mixed
Industrial
Weighted average
Butter
Grazing
Mixed
Industrial
Weighted average
Milk powder Grazing
Mixed
Industrial
Weighted average
Cheese
Grazing
Mixed
Industrial
Weighted average
Grazing
Leather
Mixed
(bovine)
Industrial
Weighted average
Green
Blue
Grey
18056
14455
4730
14507
13236
6554
745
623
304
613
438
427
55
61
96
62
9
22
10151
4809
2435
434
245
233
15
0
0
3733
4299
2056
7908
5284
4862
2893
2968
2962
2243
1435
1570
1555
780
700
517
704
4246
3808
2814
3829
3628
3253
2405
3271
3857
3459
2556
3478
17601
14090
4610
14150
240
3721
1909
651
1226
276
173
176
176
146
99
107
106
74
64
48
63
400
347
261
344
342
296
223
294
380
331
253
328
801
682
407
673
Green
Blue
Green
Blue
23729
20604
8421
19228
19440
10649
4747
11772
15860
8745
3754
8144
5482
5109
8184
6080
6363
4073
3723
4204
432
257
3625
2737
1046
1254
150
187
147
178
372
421
445
421
328
349
406
372
1689
828
215
749
35
32
24
30
24
24
28
27
22
42
16
61
244
82
1
9
12
7
0
0
0
0
318
316
525
379
364
233
213
240
25
15
213
161
7
36
16140
13227
10922
12795
9606
5337
2366
5347
5073
2765
1187
2958
11134
5401
3477
5050
4695
3005
1940
2836
3952
2351
2086
2211
1580
897
0
339
933
495
0
454
451
452
0
283
437
312
205
356
538
405
448
297
195
281
375
230
206
217
106
147
0
103
1234
398
0
14
22
14
0
0
0
0
738
542
925
648
1414
905
584
854
1189
708
628
666
128
213
25913
16192
12412
15537
11441
7528
4523
7416
8081
4544
2046
4194
3732
4068
9236
5415
11993
7676
3787
6726
10604
6309
3611
4888
1185
863
0
533
1471
722
0
582
593
582
0
381
436
393
391
893
2014
1191
1536
995
496
873
1360
815
472
635
105
132
33
122
230
0
179
104
197
0
153
126
225
22
39
196
0
117
34
167
0
100
36
178
927
8600
4880
0
5044
7348
4169
0
4309
7812
4432
145
577
799
0
789
493
683
0
674
540
742
210
696
1161
0
1141
595
992
0
975
633
1055
885
6448
4697
0
4819
5510
4013
0
4117
5857
4267
130
572
716
0
706
489
612
0
603
535
666
178
219
255
217
246
107 4581
15 14300
59 11719
235 9677
79 11323
732
0
377
904
515
1036
0
91
1093
352
4377
25195
15743
12068
15103
657
0
593
1505
777
0
247
118
656
414
336
200
205
205
173
111
121
120
20
35
43
33 1149
107 5691
192 6822
231
0
178 6254
91 4862
164 5829
198
0
152 5344
97 5169
174 6197
210
162 5681
54 22821
59 19815
93 8099
60 18445
Grey
Green
Blue
Grey
Grey
Green
0
144 10319
866 3934
288 5684
0
316 8248
484
314 8248
0
9 2443
30
13 2443
325 4048
390 3653
1021 3776
554 3723
1369 2535
876 1509
432 1548
768 1545
1176 1695
699 1085
400 1187
542 1175
34
572
65
431
500
63
462
188 3111
352 2345
0 2720
341 2513
160 2658
301 2003
0 2324
291 2147
171 2826
320 2130
2471
310 2283
0
140 11883
842 4530
280 6067
Blue
Grey
Green
Blue
15182
11615
23591
16264
14236
7176
3044
9284
7086
3615
1546
4432
7176
7212
5165
6937
8854
5259
2976
6036
411
451
1002
585
351
379
469
395
219
247
322
266
357
472
397
429
334
210
124
235
200
204
871
372
3
7
9
5
0
0
1
0
282
289
207
276
321
190
108
219
4617
4455
4511
0
1143
1488
1273
170
164
166
0
60
76
65
168
162
164
0
39
56
45
6221
8098
6927
0
5315
6920
5919
324
415
355
0
277
355
303
213
302
247
0
182
258
211
5651
7356
6292
16922
765 12946
259 26295
369 18093
310
393
338
529
574
1189
723
194
275
224
223
228
971
414
761
349
484
664
225
345
422
35
422
35
453
4
454
479
306
236
268
113
76
77
77
76
51
55
55
50
40
43
41
272
218
233
224
232
186
199
191
263
214
227
219
4
587
451
427
438
271
161
165
165
161
103
113
111
32
23
25
25
176
123
136
134
151
105
116
114
160
111
124
121
947
513
589
Grey
Green
Blue
Grey
19102
12726
2949
12933
11910
9842
0
10948
525
546
356
525
312
318
0
315
590
768
551
733
18
74
0
44
5118
4953
3404
4102
2836
1688
1731
1728
1740
1113
1218
1206
1106
582
444
647
6022
3169
2417
3519
5145
2708
2065
3007
5470
2878
2196
3196
21290
14185
3287
14450
870
743
563
645
294
183
187
187
183
121
132
130
69
59
61
60
373
321
330
324
319
274
282
277
355
307
315
310
657
681
497
658
890
916
634
761
497
296
303
303
331
212
232
230
89
88
100
89
482
478
543
483
412
409
464
413
438
435
493
439
658
856
614
819
Green
21121
14803
8849
14414
15870
7784
4607
9813
9277
4691
2431
5185
7660
5210
4050
4907
7919
4065
2337
3545
6781
3006
2298
2592
1087
790
1027
863
5913
4297
5591
4695
5052
3671
4777
4011
5371
3903
5078
4264
20905
16701
9487
15916
Blue
465
508
683
550
421
484
800
522
285
313
413
330
431
435
487
459
734
348
210
313
418
312
205
244
56
90
98
86
305
492
532
465
261
421
455
398
293
463
500
439
535
644
805
679
Grey
243
401
712
451
20
67
216
76
0
4
18
6
632
582
687
622
718
574
325
467
446
545
369
429
49
76
82
72
265
415
448
393
227
354
382
336
241
377
406
357
240
453
763
498
26 / The water footprint of farm animals and animal products
Beef
Pork
600
Blue water footprint (m 3/ton)
Blue water footprint (m 3/ton)
750
600
450
300
150
0
500
400
300
200
100
0
Grazing
Mixed
Industrial
Weighted
average
Grazing
Animal production systems
Milk
Cheese
Blue water footprint (m 3/ton)
Blue water footprint (m 3/ton)
Weighted
average
600
90
60
30
0
500
400
300
200
100
0
Grazing
Mixed
Industrial
Grazing
Weighted
average
Animal production systems
Mixed
Industrial
Weighted
average
Animal production systems
Egg
Chicken meat
600
Blue water footprint (m 3/ton)
800
Blue water footprint (m 3/ton)
Industrial
Animal production systems
120
600
400
200
400
200
0
0
Grazing
Mixed
Industrial
Grazing
Weighted
average
Mixed
Industrial
Weighted
average
Animal production systems
Animal production systems
Sheep meat
Goat meat
1000
500
Blue water footprint (m 3/ton)
Blue water footprint (m 3/ton)
Mixed
800
600
400
200
0
400
300
200
100
0
Grazing
Mixed
Industrial
Animal production systems
Weighted
average
Grazing
Mixed
Industrial
Weighted
average
Animal production systems
Figure 9. Global average blue water footprint per production system for selected animal products (1996-2005).
The water footprint of farm animals and animal products / 27
Table 5. The components of the water footprint of a beef cow and its derived products.
Feed crop*
Feed
amount
(kg/kg
carcass)
Weighted average water
footprint of feed (litre/kg)
Green
Blue
Water footprint (litre/kg carcass)
Grey
Green
Blue
Grey
Total
Maize
1.0102
695
111
181
702
112
182
996
Wheat
0.2441
1322
77
140
323
18.8
34.0
375
Barley
0.2657
1143
59
126
304
15.6
33.4
353
Soya bean cake
0.1858
1451
72
19
270
13.4
3.6
286
Sorghum
0.1028
1228
130
92
126
13.4
9.5
149
Oats
0.0603
1457
212
125
87.8
12.8
7.6
108
Rice, paddy
0.0754
997
259
165
75.1
19.6
12.4
107
Cassava
0.1451
498
0
12
72.3
0.0
1.8
74.1
Oilseed cakes, other
0.0275
2158
37
50
59.4
1.0
1.4
61.7
Rape and mustard cake
0.0479
977
132
151
46.8
6.3
7.2
60.4
Rye
0.0233
1573
38
109
36.7
0.9
2.5
40.1
Millet
0.0107
2718
130
172
29.0
1.4
1.8
32.2
Cereals, not specified
0.0308
874
66
41
26.9
2.0
1.3
30.2
Sunflower seed cake
0.0249
968
63
98
24.1
1.6
2.4
28.1
Pulses, not specified
0.0132
1133
307
618
15.0
4.1
8.2
27.2
Molasses
0.0597
311
110
29
18.6
6.6
1.7
26.9
Groundnut cake
0.0171
1265
121
106
21.7
2.1
1.8
25.6
Soybeans
0.0140
1744
41
24
24.5
0.6
0.3
25.4
Potatoes
0.0796
254
10
48
20.2
0.8
3.8
24.9
Cottonseed cake
0.0280
481
259
86
13.5
7.3
2.4
23.1
Cottonseed
0.0181
618
353
124
11.2
6.4
2.2
19.8
Peas, dry
0.0126
1149
21
336
14.4
0.3
4.2
18.9
Sunflower seed
0.0054
2744
144
234
14.8
0.8
1.3
16.9
Sugar cane
0.0698
171
35
16
11.9
2.5
1.1
15.5
Plantains
0.0091
1392
27
3
12.7
0.2
0.0
13.0
Beans, dry
0.0029
3270
48
575
9.4
0.1
1.6
11.1
Rapeseed
0.0049
1877
3
305
9.3
0.0
1.5
10.8
Vegetables fresh not specified
0.0369
152
49
69
5.6
1.8
2.5
10.0
Copra cake
0.0046
1567
2
10
7.2
0.0
0.0
7.2
Sweet potatoes
0.0170
285
7
57
4.8
0.1
1.0
5.9
Yams
0.0166
326
0
1
5.4
0.0
0.0
5.5
Palm kernel cake
0.0075
659
0
27
4.9
0.0
0.2
5.2
Dates
0.0009
2397
2074
97
2.1
1.8
0.1
4.0
Sesame seed cake
0.0015
2111
53
53
3.1
0.1
0.1
3.3
Sugar beet
0.0165
154
16
30
2.5
0.3
0.5
3.3
Oilseeds, not specified
0.0024
802
94
35
2.0
0.2
0.1
2.3
Other minor feed crops
0.0122
325
66
40
3.9
0.8
0.5
5.2
continued on next page
28 / The water footprint of farm animals and animal products
Feed crop*
Feed
amount
(kg/kg
carcass)
Weighted average water
footprint of feed (litre/kg)
Green
Blue
Water footprint (litre/kg carcass)
Grey
Green
Blue
Grey
Total
Crop residues
21.943
0
0
0
0.0
0.0
0.0
0.0
Fodder crops
2.4632
168
29
21
415
71.8
50.7
537
Pasture (grass)
31.525
303
0
0
9556
0.0
0.0
9556
Water for feed mixing
Water footprint related to feed
1.5
12391
314
1.5
388
13107
Drinking water
110
110
Service water
29
29
Total water footprint of beef cattle (litre/kg carcass)
12391
453
388
13246
1769000
64600
55300
1889000
… of which 83% is attributed to the 101 kg of resultant beef, so that
the water footprint of beef** (litre/kg beef) amounts to:
14400
550
450
15400
… of which 10% is attributed to the 18 kg of resultant offal, so that
the water footprint of offal** (litre/kg offal) amounts to:
10400
400
330
11200
… of which 5% is attributed to the 6.1 kg of resultant leather, so that
the water footprint of leather** (litre/kg leather) amounts to:
15900
680
500
17100
… of which 2% is attributed to the 0.03 kg of resultant semen, so that
the water footprint of semen** (litre/kg semen) amounts to: 1069000
40600
33400
1143000
Total water footprint of a 253 kg beef cow (in litre)
(assuming a total carcass weight of 143 kg)
* The feed amounts included here represent the global average feed intake of beef cattle. Obviously, the feed
composition of individual cows will deviate based on the production system and composition of the concentrate
feed applied.
** The percentage of the total water footprint of a beef cow attributed to each product refers to the ‘value fraction’
for that product (Appendix V). The amount of a certain product (in kg) coming from the total animal is based on
the ‘product fraction’ for that product (Appendix V). In the blue water footprint, we added the water footprint of
processing the slaughtered cow into the derived products.
3.4
Water footprint of animal versus crop products per unit of nutritional value
As a general picture we find that animal products have a larger water footprint per ton of product than crop
products. As we see from Table 6, the global average water footprint per ton of crop increases from sugar crops
(roughly 200 m3/ton) and vegetables (~300 m3/ton) to pulses (~4000 m3/ton) and nuts (~9000 m3/ton). For
animal products, the water footprint increases from milk (~1000 m3/ton) and egg (~3300 m3/ton) to beef (~15400
m3/ton). Also when viewed from a caloric standpoint, the water footprint of animal products is larger than for
crop products. The average water footprint per calorie for beef is twenty times larger than for cereals and starchy
roots. When we look at the water requirements for protein, we find that the water footprint per gram of protein
for milk, eggs and chicken meat is about 1.5 times larger than for pulses. For beef, the water footprint per gram
of protein is 6 times larger than for pulses. In the case of fat, we find that butter has a relatively small water
footprint per gram of fat, even lower than for oil crops. All other animal products, however, have larger water
footprints per gram of fat when compared to oil crops. The general conclusion is that from a freshwater resource
perspective, it is more efficient to obtain calories, protein and fat through crop products than animal products. A
note should be made here, however, that types of proteins and fats differ across the different products.
The water footprint of farm animals and animal products / 29
Table 6. The water footprint of some selected food products from vegetable and animal origin.
Water footprint per ton (m3/ton)
Food item
Nutritional content
Water footprint per unit of
nutritional value
Protein
Fat
Calorie
(litre/g (litre/g
(litre/kcal)
protein)
fat)
Green
Blue
Grey
Total
Calorie
(kcal/kg)
Protein
(g/kg)
Fat
(g/kg)
Sugar crops
130
52
15
197
285
0.0
0.0
0.69
0.0
0.0
Vegetables
194
43
85
322
240
12
2.1
1.34
26
154
Starchy roots
327
16
43
387
827
13
1.7
0.47
31
226
Fruits
726
147
89
962
460
5.3
2.8
2.09
180
348
Cereals
1232
228
184
1644
3208
80
15
0.51
21
112
Oil crops
2023
220
121
2364
2908
146
209
0.81
16
11
Pulses
3180
141
734
4055
3412
215
23
1.19
19
180
Nuts
7016
1367
680
9063
2500
65
193
3.63
139
47
Milk
863
86
72
1020
560
33
31
1.82
31
33
Eggs
2592
244
429
3265
1425
111
100
2.29
29
33
Chicken meat
3545
313
467
4325
1440
127
100
3.00
34
43
Butter
4695
465
393
5553
7692
0.0
872
0.72
0.0
6.4
Pig meat
4907
459
622
5988
2786
105
259
2.15
57
23
Sheep/goat meat
8253
457
53
8763
2059
139
163
4.25
63
54
14414
550
451
15415
1513
138
101
10.19
112
153
Bovine meat
In order to reduce the pressure on the world’s water resource associated with their consumption pattern,
individuals have the option of shifting from a meat-rich to a vegetarian diet. The water footprint of an individual
consumer depends to a large extent on the type of diet of the individual. Meat-based diets have a larger water
footprint compared to a vegetarian diet. The average USA citizen consumes almost four times the amount of
protein compared to the global average (FAO, 2009). About 63% of the daily protein intake comes from animal
based products. This high level of consumption of animal-based products is directly reflected in the relative large
water footprint of the average American citizen (Hoekstra and Chapagain, 2007). Replacing 50% of all animal
products by an equivalent amount of high nutritious crop products such as pulses, groundnuts and potatoes will
result a 30% reduction of the food-related water footprint. A vegetarian diet compared with the average current
per capita food intake in the USA can reduce the water footprint of an individual by as much as 58%.
3.5
The total water footprint of animal production
During the period 1996-2005, the total water footprint for global animal production was 2422 Gm3/yr (87.2%
green, 6.2% blue and 6.6% grey water). The different components of the global water footprint of animal
production are shown in Table 7. The largest water footprint for the animal production comes from the feed they
consume, which accounts for 98% of the total water footprint. Drinking water, service water and feed mixing
water further account only for 1.1%, 0.8% and 0.03% of the total water footprint, respectively. The estimate of
drinking and service water is in line with Peden et al. (2007). Grazing accounts for the largest share (38%),
followed by maize (17%) and fodder crops (8%).
30 / The water footprint of farm animals and animal products
The global water footprint of feed production is 2376 Gm3/yr, of which 1463 Gm3/yr refers to crops and the
remainder to grazing (Table 8). The total water footprint of feed crops amounts to 20% of the water footprint of
total crop production in the world, which is 7404 Gm3/yr (Mekonnen and Hoekstra, 2010b). The globally
aggregated blue water footprint of feed crop production is 105 Gm3/yr, which is 12% of the blue water footprint
of total crop production in the world (Mekonnen and Hoekstra, 2010b). This means that an estimated 12% of the
global consumption of groundwater and surface water for irrigation is for feed, not for food, fibres or other crop
products. Globally, the total water footprint of animal production (2422 Gm3/yr) constitutes 29% of the water
footprint of total agricultural production.
When we consider the total water footprint per animal category (Table 9), we find that beef cattle have the
largest contribution (33%) to the global water footprint of farm animal production, followed by dairy cattle
(19%), pig (19%) and broiler chicken (11%). The green, blue and grey water footprints per animal category and
production system are shown in Table 10. Altogether, mixed production systems account for the largest share
(57.4%) in the total water footprint of animal production. Grazing and industrial production systems account for
20.3% and 22.3%, respectively. In the grazing system, over 97% of the water footprint related to feed comes
from grazing and fodder crops and the water footprint is dominantly (94%) green. In the mixed and industrial
production systems, the green water footprint forms 87% and 82% of the total footprint, respectively. The blue
water footprint in the grazing system accounts for 3.6% of the total water footprint and about 33% of this comes
from the drinking and service water use. In the industrial system, the blue water footprint accounts for 8% of the
total water footprint.
Table 7. Global water footprint of animal production by component.
3
Total water footprint (Mm /yr)
Feed crop
Green
Blue
Grey
Total
Share (%)
Grazing
912816
0.0
0.0
912816
37.7
Maize
302595
33581
74960
411136
17.0
Fodder crops
167896
9900
10903
188699
7.79
Soybean cake
168221
6559
3178
177958
7.35
Wheat
122934
8345
16214
147493
6.09
Barley
116844
6778
14410
138031
5.70
Oats
48508
10370
4753
63631
2.63
Sorghum
40781
3376
2798
46954
1.94
Rice, paddy
24699
7497
4863
37059
1.53
Oilseed cakes, other
22159
409
525
23093
0.95
Rape and mustard cake
16841
2457
3134
22432
0.93
Cassava
17630
8.6
849
18488
0.76
Cereals, not else specified
15683
881
979
17543
0.72
Sweet potatoes
12927
210
2781
15918
0.66
Rye
13628
249
1057
14934
0.62
7829
1242
4300
13371
0.55
Pulses, not else specified
continued on next page
The water footprint of farm animals and animal products / 31
Total water footprint (Mm3/yr)
Feed crop
Green
Blue
Grey
Total
Share (%)
11279
626
905
12809
0.53
Potatoes
9602
369
2500
12471
0.51
Millet
9617
607
458
10682
0.44
Soybeans
9786
374
212
10372
0.43
Groundnut cake
8874
658
575
10107
0.42
Peas, dry
6666
144
1736
8546
0.35
Cottonseed cake
4851
2889
775
8514
0.35
Molasses
4214
1808
410
6432
0.27
Cottonseed
3252
2480
618
6350
0.26
Vegetables fresh not else specified
3665
703
1977
6345
0.26
Beans, dry
4003
54
922
4979
0.21
Sunflower seed
4045
200
314
4560
0.19
Rapeseed
3338
11
763
4111
0.17
Copra cake
3581
3.5
23
3608
0.15
Sugar cane
2148
590
217
2955
0.12
Palm kernel Cake
2519
0.7
93
2612
0.11
Sesame seed cake
2111
53
46
2210
0.09
Plantains
2078
52
4
2134
0.09
Sugar beet
1070
70
285
1425
0.06
Oilseeds, not else specified
990
150
50
1191
0.05
Bananas
761
53
41
855
0.04
Yams
767
0.5
3.3
771
0.03
Dates
244
279
15
538
0.02
Apples
326
118
38
483
0.02
Tomatoes
102
93
39
234
0.01
Roots and tubers, not else specified
177
4.1
27
208
0.01
Fruits, other
116
25
9
150
0.01
Groundnuts
70
8
5
83
0.00
Coconuts
38
0.0
0.1
38
0.00
Cocoa beans
16
0.0
0.2
16
0.00
Onions
0.7
1.6
0.2
2.5
0.00
Sesame seed
1.8
0.3
0.2
2.2
0.00
Palm-kernels
0.8
0.0
0.0
0.8
0.00
Mixing water for feed preparation
0.0
610
0.0
610
0.03
Sunflower seed cake
Drinking water
27099
27099
1.12
Service water
18213
18213
0.75
2421722
100.00
Total water footprint
2112301
150660
158762
32 / The water footprint of farm animals and animal products
Table 8. The global water footprint of animal production compared to the global water footprint of total agricultural
3
production for the period 1996-2005 (Gm /yr).
Green
Blue
Grey
Total
5771
899
733
7404
913
-
-
913
-
46
-
46
6684
899
733
8317
1199
105
159
1463
913
-
-
913
-
46
-
46
Total
2112
151
159
2422
Water footprint of animal production as a percentage of
the total water footprint in agricultural production
32%
17%
22%
29%
Water footprint of total agricultural production
Water footprint of crop production*
Water footprint of grazing
Direct water footprint of livestock**
Total
Water footprint of animal production
Water footprint of feed crop production
Water footprint of grazing
Direct water footprint of livestock**
* Source: Mekonnen and Hoekstra (2010b).
** Water footprint of drinking, servicing and feed mixing.
A substantial part of the water footprint of an animal product produced in one country often resides outside that
country. This is most in particular the case for products originating from industrial production systems, because
those systems use the largest fraction of concentrate feed. Feed crops are often imported rather than produced
domestically. Soybean cake, for example, which is an important feed ingredient in industrial livestock raising, is
often imported. In the period 1996-2005, 49% of global soybean production was exported, either in the form of
soybean or in the form of soybean cake (FAO, 2009).
Table 9. The total water footprint per animal category (1996-2005).
Global total number
of animals* (millions)
Average annual water footprint
3
per animal** (m /yr per animal)
Annual water footprint of
animal category (Gm3/yr)
%
Beef cattle
1267
630
798
33
Dairy cattle
228
2056
469
19
Pig
880
520
458
19
9923
26
255
11
112
1599
180
7
Layer Chicken
5046
33
167
7
Sheep
1052
68
71
3
Goat
750
32
24
1
Total
19258
2422
100
Animal category
Broiler chicken
Horse
* Source: FAO (2009).
** See Table 3.
The water footprint of farm animals and animal products / 33
Table 10. The green, blue and grey water footprints per animal category and production system (Gm3/yr) for the
period 1996-2005.
Animal category
Grazing production
system
Mixed production
system
Grey Green
Blue
Industrial production
system
Grey Green
Blue
World total
Green
Blue
Grey Green
Blue Grey
Beef cattle
185
4.5
2.1
443
20
12
112
10
9.0
740
35
23
Dairy cattle
83
3.6
3.7
269
27
26
48
4.1
3.8
400
35
34
Pig
27
1.5
2.2
237
19
27
111
14
19
376
34
48
Broiler chicken
37
3.4
3.3
100
8.3
14
73
6.3
10
210
18
28
Horse
82
3.0
1.4
69
7.1
2.4
13
0.8
0.6
164
11
4
Layer chicken
4.5
0.3
0.3
52
5.4
9.4
77
6.5
12
133
12
22
Sheep
34
1.2
0.0
28
2.0
0.2
5.0
1.0
0.2
66.5
4.3
0.5
Goat
8.2
0.3
0.0
13
0.9
0.0
2.0
0.4
0.0
22.7
1.5
0.0
Total
461
17.8
13.2
1210
90
90
442
43
55
2112
151
159
4. Discussion
The result of the current study can be compared with results from earlier studies. However, only a few other
studies on the water footprint per unit of animal product and the total water footprint of animal production are
available. We will first compare our estimates of the water footprints per ton of animal product with two earlier
studies and subsequently we will compare the total water footprint related to animal feed production with five
earlier studies.
The rough estimates made by Pimentel et al. (2004) for the water footprints of beef and meat from sheep, pig and
chicken are partly very close to our global estimates but partly also quite different. They report a water footprint
of chicken meat of 3500 m3/ton, which is only a bit lower than our global average estimate of 4300 m3/ton, and
even closer if we subtract the grey water footprint component from our estimate (which is not included in
Pimentel’s studies). They report a water footprint of pig meat of 6000 m3/ton, which happens to coincide with
our global average estimate (but our estimate includes the grey water footprint component). For sheep meat, they
report a water footprint of 51000 m3/ton and for beef 43000 m3/ton, values that are very high when compared to
our estimates (10,400 m3/ton for sheep meat and 15400 m3/ton for beef). We consider the values reported by
Pimentel as crude first estimates, for which the underlying assumptions have not been spelled out, so that it is
difficult to explain differences with our estimates.
The study of Chapagain and Hoekstra (2004) is the only publication with global estimates of the water footprint
of animal products with specifications by country. At a global level, the estimated water footprints per ton of
animal and animal product compare very well with the estimates from Chapagain and Hoekstra (2004), with an r2
of 0.88 (Figure 10a). The good agreement at the global level between the two studies is probably that the global
average water footprints for various feed ingredients are very close in the two studies. The trend line in Figure
10a is slightly above 1, which is caused by our higher estimates for the water footprints of sheep and goat meat.
For most other animal products, the current study gives a bit lower estimates than the earlier study.
When we compare our estimates with Chapagain and Hoekstra (2004) at a country level, more differences are
found (Figure 10b-f). The two studies show a relatively good agreement for pig meat, chicken meat and egg –
although for egg the earlier study systematically gives higher numbers – but little agreement for beef and dairy
products. In general we find that Chapagain and Hoekstra (2004) underestimated the water footprints for African
countries and overestimated the water footprints for OECD countries. As already pointed out in the introductory
chapter, there are three main reasons why the estimates from the current study can differ from the 2004-study
and are considered more accurate. First, the current study is based on better data for the estimation of the
quantity and composition of animal feed. Second, the current study reckons with the relative presence of the
three production systems per country and accounts for the differences between those systems. Third, we have
estimated the water footprints of the various feed ingredients more accurately by using a high-resolution gridbased crop water use model, including the effect of water deficits where they occur, making explicit distinction
between the green and blue water footprint components and including the grey water footprint component.
36 / The water footprint of farm animals and animal products
trend line
1:1 line
y = 1.0246x
R² = 0.8773
15000
beef
10000
sheep meat
beef cattle
goat meat
5000
pig meat
milk
0
0
5000
10000
15000
20000
100000
Beef WF estimate from current study [m 3/ton]
Animals and animal products WF estimate
from current study [m 3/ton]
20000
1:1 line
75000
Cyprus
Syria
Mongolia
25000
Morocco
Mostly
OECD
countries
Mexico
Spain
0
0
25000
50000
75000
100000
Beef WF estimate from Chapagain and Hoekstra (2004) [m 3/ton]
Portk WF estimate from current study [m 3/ton]
Milk WF estimate from current study [m 3/ton]
Tunisia
Ertrea
Benin
(b)
10000
y = 0.835x
R² = 0.4798
trend line
1:1 line
7500
5000
Mauritania
Senegal
Niger
Hungary
2500
Georgia
Mongolia
0
0
2500
5000
7500
20000
trend line
1:1 line
y = 0.891x
R² = 0.7929
15000
10000
Tajikstan
5000
0
0
10000
5000
10000
15000
20000
Pork WF estimate from Chapagain and Hoekstra (2004) [m 3/ton]
Milk WF estimate from Chapagain and Hoekstra (2004) [m 3/ton]
(c)
(d)
20000
trend line
1:1 line
Egg WF estimate from current study [m 3/ton]
Chicken meat WF estimate from current study
[m 3/ton]
Bolivia
Mostly
African
countries
50000
Animals and animal products WF estimate from Chapagain and Hoekstra (2004)
[m 3/ton]
(a)
y = 0.8917x
R² = 0.2649
trend line
y = 0.9369x
R² = 0.8717
15000
10000
5000
0
20000
trend line
1:1 line
y = 0.6422x
R² = 0.6972
15000
10000
5000
0
0
5000
10000
15000
20000
0
Chicken meat WF estimate from Chapagain and Hoekstra (2004) [m 3/ton]
(e)
5000
10000
15000
20000
Egg WF estimate from Chapagain and Hoekstra (2004) [m 3/ton]
(f)
Figure 10. Comparison of average water footprint of (a) animals and animal products at global level, and (b) beef
(c) milk, (d) pig meat, (e) chicken meat and (f) egg at the country level as estimated in the current study and
Chapagain and Hoekstra (2004). From the current study we show here the sum of green and blue water
footprints, excluding the grey water footprint, because that component was excluded in the 2004-study.
As one can see in the overview presented in Table 11, our estimate of the total evaporative water use (green plus
blue water footprint) for producing animal feed (2217 Gm3/yr) is 3% larger than the estimate by De Fraiture et al.
(2007) and 5% smaller than the estimate by Zimmer and Renault (2003). Our estimate of the global consumptive
water use for producing feed crops (1312 Gm3/yr) does not significantly differ from the estimate by De Fraiture
et al. (2007). Our estimate of global consumptive water use for grazing (913 Gm3/yr) is 9% larger than the
estimate by De Fraiture et al. (2007). The differences with three other studies that reported on the consumptive
water use related to grazing are much larger, which is cause by another definition applied. Postel et al. (1996)
estimated the water evaporated from grazing land to be 5800 Gm3/yr. In more recent studies, Rost et al. (2008)
and Hanasaki et al. (2010) estimate the total evapotranspiration from grazing land to be 8258 Gm3/yr and 12960
Gm3/yr, respectively. However, unlike the current study, the estimates in these three studies refer to the total
evapotranspiration from grazing lands rather than to the evaporation related to the grass actually consumed.
The water footprint of farm animals and animal products / 37
According to De Fraiture et al. (2007), reported ‘grazing lands’ are only partly actually grazed. Besides, the
harvest efficiency – the fraction of grass actually consumed by the animal compared to the standing biomass – is
quite small. In a recent study in the USA, Smart et al. (2010) showed that, depending on the animal stocking
density, harvest efficiencies reach between 14-38%.
Table 11. Comparison of the results of the current study with the results from previous studies.
Period
3
Global water footprint* related to animal feed production (Gm /yr)
Study
Grazing
Crops
Total
Postel et al. (1996)
1995
5800
-
-
Zimmer and Renault (2003)
2000
-
-
2340
De Fraiture et al. (2007)
2000
840
1312
2152
Rost et al. (2008)
1971-2002
8258
-
-
Hanasaki et al. (2010)
1985-1999
12960
-
-
Current study*
1996-2005
913
1304
2217
* The numbers in the table, also the ones from the current study, refer to the green plus blue water footprint. None
of the previous studies included the grey water footprint component.
There are several uncertainties in this study in the quantification of the water footprint of animals and animal
products. Due to a lack of data, many assumptions have to be made. There are a number of uncertainties in the
study, but particularly two types of uncertainty may have a major effect on the final output of the study. First,
data on animal distribution per production system per country for OECD countries is not available. Wint and
Robinson (2007) provide livestock distributions per production system per country for developing countries but
not for OECD countries. For these countries we are forced to use the data from Seré and Steinfeld (1996), who
provide livestock distribution per economic region. These data have the limitation that they are not countryspecific and may lead to wrong distribution of animals into the different production system for some countries.
The second major uncertainty is related to the precise composition of feed per animal category per country. Such
data are not directly available so that we had to infer these data by combining different data sources and a
number of assumptions.
Although the scope of this study is very comprehensive, there are many issues that have been left out. One issue
is that we neglected the indirect water footprints of materials used in feed production and animal raising. We
expect that this may add at most a few per cents to the water footprint estimates found in this study (based on
Hoekstra et al., 2009). In the grey water footprint estimations we have looked at the water pollution by nitrogenfertilisers only, excluding the potential pollution by other fertiliser components or by pesticides or other agrochemicals. Besides, we have not quantified the grey water footprint coming from animal wastes, which is
particularly relevant for industrial production systems. Intensive animal production often generates an amount of
waste that cannot be fully recycled on the nearby land. The large amount of waste generated in a concentrated
place can seriously affect freshwater systems (FAO, 2005; Steinfeld et al., 2006; Galloway et al., 2007). Finally,
by focusing on freshwater appropriation, the study obviously excludes many other relevant issues in farm animal
production, such as micro- and macro-cost of production, livelihood of smallholder farmers, animal welfare,
public health and environmental issues other than freshwater.
5. Conclusion
The present study estimates the water footprint of farm animals and animal products per production system and
per country. The results show that:

Although beef cattle, sheep and goat require much more feed per unit of meat produced than pig and broiler
chicken, the fraction of concentrate feed in the total feed is much larger for the latter (Section 3.1). Since
concentrate feed has a larger water footprint per unit of weight than roughages (Section 3.2), the water
footprints of the different sorts of meat are closer than one would expect on the basis of feed conversion
efficiencies alone (Section 3.3).

The total water footprint of an animal product is generally larger when obtained from a grazing system than
when produced from an industrial system, because of a larger green water footprint component. The blue and
grey water footprints of animal products are largest for industrial systems (with an exception for chicken
products). From a freshwater perspective, animal products from grazing systems are therefore to be preferred
above products from industrial systems (Section 3.3).

The water footprint of any animal product is larger than the water footprint of a wisely chosen crop product
with equivalent nutritional value (Section 3.4).

29% of the total water footprint of the agricultural sector in the world is related to the production of animal
products. One third of the global water footprint of animal production is related to beef cattle (Section 3.5).
The global meat production has almost doubled in the period 1980-2004 (FAO, 2005) and this trend is likely to
continue given the projected doubling of meat production in the period 2000-2050 (Steinfeld et al., 2006). To
meet this rising demand for animal products, the on-going shift from traditional extensive and mixed farming to
industrial farming systems is likely to continue. Because of the larger dependence on concentrate feed in
industrial systems, this intensification of animal production systems will result in increasing blue and grey water
footprints per unit of animal product. The pressure on the global freshwater resources will thus increase both
because of the increasing meat consumption and the increasing blue and grey water footprint per unit of meat
consumed.
Managing the demand for animal products by promoting a dietary shift away from a meat-rich diet will be an
inevitable component in the environmental policy of governments. In countries where the consumption of animal
products is still quickly rising, one should critically look how this growing demand can be moderated. On the
production side, it would be wise to include freshwater implications in the development of animal farming
policies, which means that particularly feed composition, feed water requirements and feed origin need to receive
attention. Animal farming puts the lowest pressure on freshwater systems when dominantly based on crop
residues, waste and roughages. Policies aimed to influence either the consumption or production side of farm
animal products will generally entail various sorts of socio-economic and environmental trade-offs (Herrero et
al., 2009; Pelletier and Tyedmers, 2010). Therefore, policies aimed at reducing the negative impacts of animal
production and consumption should be able to address these potential tradeoffs. Policies should not affect the
40 / The water footprint of farm animals and animal products
required increase in food security in less developed countries neither the livelihood of the rural poor should be
put in danger through intensification of animal farming.
This study provides a rich data source for further studies on the factors that determine how animal products put
pressure on the global water resources. The reported incidents of groundwater depletion, rivers running dry and
increasing levels of pollution form an indication of the growing water scarcity (UNESCO, 2009; Postel, 2000;
Gleick, 1993). Since animal production and consumption play an important role in depleting and polluting the
world’s scarce freshwater resources, information on the water footprint of animal products will help us
understand how we can sustain the scarce freshwater resources.
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food system, PhD thesis, Chalmers University of Technology and Göteborg University, Göteborg, Sweden,
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Zimmer, D. and Renault, D. (2003) Virtual water in food production and global trade: review of methodological
issues and preliminary results, In: Hoekstra, A.Y. (ed.) Virtual water trade: Proceedings of the
International Expert Meeting on Virtual Water Trade, Value of Water Research Report Series No.12,
UNESCO-IHE, Delft, The Netherlands, pp. 93-109.
Value of Water Research Report Series
Editorial board:
Arjen Y. Hoekstra – University of Twente, a.y.hoekstra@utwente.nl
Hubert H.G. Savenije – Delft University of Technology, h.h.g.savenije@tudelft.nl
Pieter van der Zaag – UNESCO-IHE Institute for Water Education, p.vanderzaag@unesco-ihe.org
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Exploring methods to assess the value of water: A case study on the Zambezi basin.
A.K. Chapagain  February 2000
Water value flows: A case study on the Zambezi basin.
A.Y. Hoekstra, H.H.G. Savenije and A.K. Chapagain  March 2000
The water value-flow concept.
I.M. Seyam and A.Y. Hoekstra  December 2000
The value of irrigation water in Nyanyadzi smallholder irrigation scheme, Zimbabwe.
G.T. Pazvakawambwa and P. van der Zaag – January 2001
The economic valuation of water: Principles and methods
J.I. Agudelo – August 2001
The economic valuation of water for agriculture: A simple method applied to the eight Zambezi basin countries
J.I. Agudelo and A.Y. Hoekstra – August 2001
The value of freshwater wetlands in the Zambezi basin
I.M. Seyam, A.Y. Hoekstra, G.S. Ngabirano and H.H.G. Savenije – August 2001
‘Demand management’ and ‘Water as an economic good’: Paradigms with pitfalls
H.H.G. Savenije and P. van der Zaag – October 2001
Why water is not an ordinary economic good
H.H.G. Savenije – October 2001
Calculation methods to assess the value of upstream water flows and storage as a function of downstream benefits
I.M. Seyam, A.Y. Hoekstra and H.H.G. Savenije – October 2001
Virtual water trade: A quantification of virtual water flows between nations in relation to international crop trade
A.Y. Hoekstra and P.Q. Hung – September 2002
Virtual water trade: Proceedings of the international expert meeting on virtual water trade
A.Y. Hoekstra (ed.) – February 2003
Virtual water flows between nations in relation to trade in livestock and livestock products
A.K. Chapagain and A.Y. Hoekstra – July 2003
The water needed to have the Dutch drink coffee
A.K. Chapagain and A.Y. Hoekstra – August 2003
The water needed to have the Dutch drink tea
A.K. Chapagain and A.Y. Hoekstra – August 2003
Water footprints of nations, Volume 1: Main Report, Volume 2: Appendices
A.K. Chapagain and A.Y. Hoekstra – November 2004
Saving water through global trade
A.K. Chapagain, A.Y. Hoekstra and H.H.G. Savenije – September 2005
The water footprint of cotton consumption
A.K. Chapagain, A.Y. Hoekstra, H.H.G. Savenije and R. Gautam – September 2005
Water as an economic good: the value of pricing and the failure of markets
P. van der Zaag and H.H.G. Savenije – July 2006
The global dimension of water governance: Nine reasons for global arrangements in order to cope with local water problems
A.Y. Hoekstra – July 2006
The water footprints of Morocco and the Netherlands
A.Y. Hoekstra and A.K. Chapagain – July 2006
Water’s vulnerable value in Africa
P. van der Zaag – July 2006
Human appropriation of natural capital: Comparing ecological footprint and water footprint analysis
A.Y. Hoekstra – July 2007
A river basin as a common-pool resource: A case study for the Jaguaribe basin in Brazil
P.R. van Oel, M.S. Krol and A.Y. Hoekstra – July 2007
Strategic importance of green water in international crop trade
M.M. Aldaya, A.Y. Hoekstra and J.A. Allan – March 2008
26. Global water governance: Conceptual design of global institutional arrangements
M.P. Verkerk, A.Y. Hoekstra and P.W. Gerbens-Leenes – March 2008
27. Business water footprint accounting: A tool to assess how production of goods and services impact on freshwater
resources worldwide
P.W. Gerbens-Leenes and A.Y. Hoekstra – March 2008
28. Water neutral: reducing and offsetting the impacts of water footprints
A.Y. Hoekstra – March 2008
29. Water footprint of bio-energy and other primary energy carriers
P.W. Gerbens-Leenes, A.Y. Hoekstra and Th.H. van der Meer – March 2008
30. Food consumption patterns and their effect on water requirement in China
J. Liu and H.H.G. Savenije – March 2008
31. Going against the flow: A critical analysis of virtual water trade in the context of India’s National River Linking
Programme
S. Verma, D.A. Kampman, P. van der Zaag and A.Y. Hoekstra – March 2008
32. The water footprint of India
D.A. Kampman, A.Y. Hoekstra and M.S. Krol – May 2008
33. The external water footprint of the Netherlands: Quantification and impact assessment
P.R. van Oel, M.M. Mekonnen and A.Y. Hoekstra – May 2008
34. The water footprint of bio-energy: Global water use for bio-ethanol, bio-diesel, heat and electricity
P.W. Gerbens-Leenes, A.Y. Hoekstra and Th.H. van der Meer – August 2008
35. Water footprint analysis for the Guadiana river basin
M.M. Aldaya and M.R. Llamas – November 2008
36. The water needed to have Italians eat pasta and pizza
M.M. Aldaya and A.Y. Hoekstra – May 2009
37. The water footprint of Indonesian provinces related to the consumption of crop products
F. Bulsink, A.Y. Hoekstra and M.J. Booij – May 2009
38. The water footprint of sweeteners and bio-ethanol from sugar cane, sugar beet and maize
P.W. Gerbens-Leenes and A.Y. Hoekstra – November 2009
39. A pilot in corporate water footprint accounting and impact assessment: The water footprint of a sugar-containing
carbonated beverage
A.E. Ercin, M.M. Aldaya and A.Y. Hoekstra – November 2009
40. The blue, green and grey water footprint of rice from both a production and consumption perspective
A.K. Chapagain and A.Y. Hoekstra – March 2010
41. Water footprint of cotton, wheat and rice production in Central Asia
M.M. Aldaya, G. Muñoz and A.Y. Hoekstra – March 2010
42. A global and high-resolution assessment of the green, blue and grey water footprint of wheat
M.M. Mekonnen and A.Y. Hoekstra – April 2010
43. Biofuel scenarios in a water perspective: The global blue and green water footprint of road transport in 2030
A.R. van Lienden, P.W. Gerbens-Leenes, A.Y. Hoekstra and Th.H. van der Meer – April 2010
44. Burning water: The water footprint of biofuel-based transport
P.W. Gerbens-Leenes and A.Y. Hoekstra – June 2010
45. Mitigating the water footprint of export cut flowers from the Lake Naivasha Basin, Kenya
M.M. Mekonnen and A.Y. Hoekstra – June 2010
46. The green and blue water footprint of paper products: methodological considerations and quantification
P.R. van Oel and A.Y. Hoekstra – July 2010
47. The green, blue and grey water footprint of crops and derived crop products
M.M. Mekonnen and A.Y. Hoekstra – December 2010
48. The green, blue and grey water footprint of farm animals and animal products
M.M. Mekonnen and A.Y. Hoekstra – December 2010
Reports can be downloaded from:
www.waterfootprint.org
www.unesco-ihe.org/value-of-water-research-report-series
UNESCO-IHE
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University of Twente
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